Motor Nameplate and Table 430.250 2

[electcite]

I don't have many chances to see the motors in the real life. My question is Table 430.250 (HP, Amps) in the NEC is exactly the same as shown on the motor nameplate? Thanks.

 

[davidbeach]

Nope, you don't need motor nameplate until you are ready to select to overload heaters in the starter. Everything else is based on the code tables.

 

[dpc]

You would use the data in the Table in lieu of motor full load amps in most cases. The actual full load amp rating listed on the motor nameplate will vary slightly based on the motor manufacturer, efficiency, power factor, motor design etc. The nameplate full load amps will almost always be slightly less than the value in the table if you are dealing with 1200 rpm to 3600 rpm motors. For very slow speed motors, or special purpose motors, the nameplate amps can be higher than what is listed. Then you have to use the actual nameplate amps.

The NEC table is used as the basis for conductor sizing to establish a baseline that is applicable to large majority of the motors in use.

 

[alehman]

The primary exception to that is packaged HVAC equipment, where a different set of rules apply. That's primarily because motors in that type of equipment are typically not marked or even rated with horsepower values.